A rebel militiaman stands guard at a Libyan oil refinery in Brega. Photograph: John Moore/Getty Images

5.19pm: Here are today's key events on another eventful day for Libya:

• The Libyan government has accepted a Venezuelan proposal to seek a negotiated solution to the crisis in the country, according to Hugo Chavez's information minister (see 3.53pm). It is unclear how exactly this initiative would work and whether it would help (see 12.46pm).

• Muammar Gaddafi and his sons are to be investigated by the international criminal court for possible crimes against humanity. Prosecutor Luis Moreno-Ocampo said Gaddafi's security forces were alleged to have attacked peaceful demonstrators in several towns and cities across Libya since 15 February. Gaddafi has denied using violence against demonstrators, whom he has described as agents of al-Qaida. International media have been unable to witness the worst of the reported incidents.

• Brega and Ajdabiya have reportedly been bombed by Gaddafi's forces as troops loyal to the Libyan leader continue their bid to reclaim towns and cities controlled by anti-Gaddafi demonstrators. Reuters reported that the airport in Brega was targeted, while strikes in Ajdabiya were aimed at forces massed at the city's western gate.

• Khaled Att-ardi, a man from Manchester who was born in Tripoli, has reportedly been killed in Libya (see 4.24pm). A British citizen who had lived in Manchester for 13 years, Mr Att-ardi had reportedly gone to Libya to bring back his daughter.

The businessman, from the Whalley Range district of Manchester, had travelled to Libya a fortnight ago to get his 20-year-old daughter Fatima out of the capital, Tripoli.

A close friend of the family, Nadia Handi, 40, told the Manchester Evening News his wife Monya had become frantic after being unable to contact him and at first refused to believe it when a friend called from Libya to say he had been killed.

She said: "He was going to Libya to bring back their daughter and now he is dead. Monya is devastated, she can't talk at all. She can't concentrate, or eat or drink.

"The children are all crying, I can't explain how horrible it is."

Ms Handi said her friend, who was born in Tripoli, had been in Manchester for 13 years and was a British citizen.

His youngest child, Layla, is 18 months old.

The Guardian has not been able to establish contact with Handi or the dead man's relatives.

6.12pm: This is David Batty - I'm taking over the live blog for the evening.

AP has more on the international effort to evacuate tens of thousands of foreign workers from along Libya's borders. Almost 200,000 have now crossed from Libya into Tunisia, Egypt and Niger, according to the International Organisation for Migration, which was involved in efforts to evacuate 5,500 migrants from Benghazi on Thursday.

The IMO said nine flights provided by Britain and the UN refugee agency were flying nearly 1,700 people from Djerba, Tunisia, to Cairo. The first to be airlifted out were about 200 women, children and medical patients. Evacuees-in-waiting were mostly from Bangladesh, India and Sudan, and a few from Syria and Ghana, AP reports.

About 3,000 Bangladeshis and 1,000 northern Sudanese remain trapped in a no-man's land between Libya and Egypt. IMO officials said one African worker told them 6,000-10,000 other foreigner labourers, families and pregnant women were trapped in Khomees, including West Africans, Chinese and Filipinos.

Reuters reports than Egyptian migrant were taken by bus from the UN relief agency transit camp near the frontier to Djerba airport where around 40 evacuation flights were due to fly them out to Cairo during the day.

"The total number of people who have crossed so far, from Feb. 20 to today, is from 90,000 to 95,000," Firas Kayal of the UNHCR told the news agency. "Yesterday alone there were 9,000 with Bangladeshis the majority."

6.39pm: Barack Obama says Gaddafi has lost his legitimacy to lead and "must leave".

The White House news conference was the first time that the US president has appeared in person to demand the Libyan leader step down.

"We will continue to send a clear message: the violence must stop. Muammar Gaddafi has lost the legitimacy to lead and he must leave. Those who perpetrate violence against the Libyan people will be held accountable. The aspirations of the Libyan people for freedom, democracy and dignity must be met."

Obama also said he had authorised US AID, the state humanitarian agency, to charter civilian aircraft "to help people from other countries to find their way home".

6.46pm: The anti-Gaddafi National Libyan Council in Benghazi has responded to Venezuela's offer to mediate talks with Gaddafi.

The opposition council said they were only open to talks on Gaddafi's resignation or exile to stop the bloodshed, Reuters reports.

Ahmed Jabreel, an aide to ex-justice minister Mustafa Abdel Jalil who heads the council, also told the news agency that air strikes to set up a "no-fly" zone were needed to help topple Gaddafi.

"If there is any negotiation it will be on one single thing - how Gaddafi is going to leave the country or step down so we can save lives. There is nothing else to negotiate.

"The military council in Benghazi started organising themselves they have not taken any decision to move to the west but they are organising themselves so they can be ready for any development in the coming days."

6.55pm: AP has published an analysis piece, assessing what Gaddafi's options are.

Marina Ottaway, director of the Middle East programme in at the Carnegie Endowment think tank, told the news agency:

"Gadhafi is boxed in. At best, he could hope to be given asylum in Zimbabwe or perhaps Chad. The main question is how long he will have people willing to defend him."

Another defence analyst reckons that Gadhafi's threats to fight to the end could prompt the West to intervene sooner.

Anthony Cordesman, of the Center for Strategic and International Studies in Washington, said: "The problem is that whenever Gadhafi escalates, the West will escalate back. If he executes those threats, he will force the West to become more engaged."

Ultimately the despot's fate is in the hands of his defenders in Tripoli - hundreds of mercenaries and a brigade led by and named after one of his sons, Khamis, Goerge Joffe, a North Africa expert at Cambridge University, told the news agency.

"As long as they remain loyal to him, he can survive," said Joffe.

However, Joffe noted that Gaddafi's money for the mercenaries could run out given the international sanctions imposed on his regime.

But AP suggests that money may not be the mercenaries only concern.

"We foreigners don't have much choice, we have to support Gadhafi. It is because of him we are here," said a mercenary from neighbouring Mali, who has the rank of a sergeant in the Libyan army.

The mercenary added that the only way Gaddafi would go was if someone put a bullet in his head.

"I can't imagine that. The soldiers close to him would never let it happen."

7.09pm: Obama has said the US and the rest of the international community must be ready to act rapidly if the humanitarian crisis or violence in Libya worsens.

The US president said his administration was preparing a full range of options to tackle the crisis in order to avoid his choices from being "hamstrung", Reuters reports. He suggested that if Gaddafi was "hunkered down" in Tripoli, the US might have to find a way to get food aid to Libyans.

7.25pm: British foreign secretary William Hague has denied that the UK is out of step with its closest allies over Libya.

His comments came after the US defence secretary, Robert Gates, appeared to dismiss calls by the prime minister, David Cameron, for a no-fly zone over Libya when he warned against "loose talk" about military intervention.

But following talks in Paris with his French counterpart, Alain Juppe, Hague said the UK was "absolutely in a line" with the US and France on the possible imposition of a no-fly zone.

"We are not proposing a no-fly zone at the moment, we are simply proposing the planning of that," he told the BBC.

"None of these options are pain-free or simple but, as the prime minister has said, if people were being attacked in huge numbers, then it is unlikely the world will just stand idly by."

"Rebels captured 6 african mercenaries in eastern libya today. Almost summarily executed them. A colleague stopped things. The captured mercenaries said they had entered #libya through an air force base in the south."

7.33pm: Pro-Gaddafi forces captured three Dutch marines and their helicopter during a botched evacuation mission, the Dutch defence ministry has admitted.

Libyan authorities are still holding the marines five days after they were seized on Sunday after landing near Sirte in a Lynx helicopter from the navy ship HMS Tromp, AP reports.

Two Europeans, one Dutch and one whose nationality was not released, were also captured. They were handed over unharmed to the Dutch embassy in Tripoli early on Thursday and have left Libya, the ministry said.

Dutch officials are in "intensive negotiations" with Gadhafi's government to secure the marines' release, prime minister Mark Rutte said.

7.42pm: Mariah Carey, one of several stars criticised for performing at lavish parties hosted by the Gaddafi family, has sought to distance themselves from the controversy.

In a statement on her website, Carey confirmed she had performed at a party "thrown by the sons of vicious, crazy dictator" Gaddafi and expressed her embarrassment.

"At the time, Libya was not in the news...Now it's become an issue in hindsight, which is sort of ridiculous. I was naive and unaware of who I was booked to perform for.I feel horrible and embarrassed to have participated in this mess.

"Going forward, this is a lesson for all artists to learn from. We need to be more aware and take more responsibility regardless of who books our shows. Ultimately we as artists are to be held accountable."

7.59pm: A British oil worker who has returned home to Scotland after escaping from the Libyan desert has told the BBC about his ordeal.

Jim Coyle, 57, from Erskine, Renfrewshire, escaped from the compound in the Amal desert in a convoy of 20 vehicles. He and colleagues travelled to the Egyptian border to reach safety.

He told the BBC at Glasgow Airport that he was pleased and delighted to return home.

"I've come through so much. This is like eight weeks since I've last seen my family.

"We organised a 20-car convoy. It was very, very difficult to organise that. We were in the middle of it all in the desert. I've left a lot of good friends - the friends that protected me and everybody else with a baseball bat against the insurgents."

8.03pm: Around 400 US Marines have arrived at an American naval base in Greece as part of a military build up to allow the Obama administration more scope to respond to the Libyan crisis, AP reports.

Although the Pentagon has tried to play down the idea of military intervention, a spokesman for the Souda Bay base on the island of Crete said the marines have been deployed "as part of contingency planning to provide the president flexibility on full range of options regarding Libya."

Their deployment follows the arrival of the amphibious assault ships USS Kearsarge and USS Ponce in Mediterranean Sea.

8.11pm: Venezuela's information minister has said more about President Hugo Chavez proposal to mediate a resolution to the crisis in Libya.

In a post on Twitter, Andres Izarra said Venezuela's foreign minister spoke with his Libyan counterpart who confirmed Gaddafi's support for the peace initiative.

Izarra said Chavez had spoken with Gaddafi about creating a bloc of friendly countries to help mediate.

Izarra also said that several Latin American foreign ministers belonging to the Bolivarian Alternative bloc will discuss the peace proposal at a meeting on March 11.

8.37pm: Algeria has denied allegations by Libyan rebels that it is giving support to Gaddafi, Reuters reports.

"I strongly deny this information. It is absolutely inconceivable," Halim Benatallah, a ministerial delegate in charge of Algerian expatriates, told the news agency.

"On the contrary, Algeria is playing its humanitarian role by trying to help as much as it can."

The rebel National Libyan Council claimed on Wednesday there was evidence that the Algerian government was involved in sending African troops to support Gaddafi's regime.

The university's reputation has taken a battering over links with the Libyan regime, which include a donation of £1.5m from a charitable foundation run by one of Muammar Gaddafi's sons, Saif al-Islam, who studied at the LSE. On Tuesday, the LSE agreed to put £300,000, equivalent to the cash it has received from the foundation, into a scholarship for north African students.

But that was not enough to draw a line under the affair. On Thursday morning, a report of the WikiLeaks claims was circulated to members of the LSE council, its governing body in advance of a crisis meeting on Thursday night.

The council has commissioned an independent inquiry into the university's relationship with Libya and with Saif Gaddafi.

Davies said he had made a mistake in accepting money from the Gaddafi regime:

"I have concluded that it would be right for me to step down even though I know that this will cause difficulty for the institution I have come to love. The short point is that I am responsible for the school's reputation, and that has suffered.

"I advised the council that it was reasonable to accept the money and that has turned out to be a mistake. There were risks involved in taking funding from sources associated with Libya and they should have been weighed more heavily in the balance."

He also admitted making a "personal error of judgment" in travelling to Libya himself.

"Also, I made a personal error of judgment in accepting the British government's invitation to be an economic envoy and the consequent Libyan invitation to advise their sovereign wealth fund.

"There was nothing substantive to be ashamed of in that work and I disclosed it fully, but the consequence has been to make it more difficult for me to defend the institution."

Davies, a former head of the Financial Services Authority and deputy governor of the Bank of England, will remain in his post until a successor has been found.

10.12pm: Here's more on the independent inquiry into LSE's links with Libya.

The inquiry will be conducted by Lord Woolf, former Lord Chief Justice of England and Wales and former chairman of the Council of University College London. Its aim will be to clarify the extent of the university's links with Libya and to establish guidelines for international donations in the future. The inquiry will look at the acceptance of a £1.5m donation from the Gaddafi International Charity and Development Foundation (GICDF) in 2009, £300,000 of which has been received so far.

10.14pm: US officials have expressed little enthusiasm for Venezuelan President Hugo Chavez's proposal to mediate a peace settlement between Gaddafi and the rebels, Reuters reports.

"It's uncertain to me what an international commission is going to accomplish. Colonel Gaddafi needs to step down," state department spokesman PJ Crowley said.

10.27pm: Seemingly contradicting his father, Saif al-Islam Gaddafi has said there's no need for foreign mediation to solve Libya's crisis. In an interview with Sky News he thanked Venezuela for their offer to mediate between his father's regime and the rebels, but said they were more than capable of solving their own issues.

10.52pm: Rebel forces pushed west on Thursday to extend their grip on a key coast road west of the town of Brega where they engaged pro-Gaddafi forces in a fierce battle on Wednesday, Reuters reports.

The opposition fighters said they had driven back troops loyal to Gaddafi to Ras Lanuf, site of another major oil terminal and 600 km (375 miles) east of Tripoli.

They also told the news agency that they had captured a group of African mercenaries.

In an angry scene at al-Uqayla, east of Ras Lanuf, a rebel shouted at a captured young African and alleged mercenary: "You were carrying guns, yes or no? You were with Gaddafi's brigades yes or no?"The silent youth was shoved onto his knees into the dirt. A man held a pistol close to the boy's face before a reporter protested and told the man the rebels were not judges.

Meanwhile, the spokesman for the Revolution's military council in Benghazi has told Al Jazeera that they have 10,000 recruits and volunteers ready to fight to liberate cities in the west of Libya.

11.04pm: Sky News has an interview with Saif al-Islam Gaddafi in which the Libyan dictator's son says bombs were dropped in Brega to scare protesters.

11.55pm - Tunisia: An election will be held in Tunisia on July 24 to choose an assembly that will rewrite the constitution and oversee the country's transition following the overthrow of Zine al-Abidine Ben Ali, Reuters reports.

in a televised speech, interim president Fouad Mebazza said he and a caretaker government would stay in power until the election was held.

"We are proclaiming today that we are entering a new era ... and a new political system which definitively breaks with the ousted regime."

A source close to the president's office told Reuters that, once elected, the council could either appoint a new government or ask the caretaker executive to carry on until presidential and parliamentary elections were held.

Here's the account of one man who says his brother was taken at 3.30am on Wednesday after a dozen four-wheel-drives arrived in the square where his extended family lives.

"Fifteen of them came and kicked in the door. They turned the house upside down. In this neighbourhood, 20 have disappeared. We don't know where they have gone.

"The people in this area feel threatened. They are scared. The government says if there are any protests in the streets here they will burn them.

"I don't sleep at night. After what has happened no one wants to sleep in their houses any more. We don't know who is with us and who's against us," he says. "They know who we are. When you go in the street [to demonstrate] they take your names and photograph who's there. They call this area a terrorist area that is against Muammar. I hide in rooms outside the area."

12.17am: That concludes our live coverage of the conflict in Libya.

Our rolling coverage will continue in another blog later on Friday morning. In the meantime here's a recap of Thursday's main developments:

•US president Obama has for the first time publicly declared that Gaddafi has lost legitimacy and should leave.

•Fighting between Gaddafi loyalists and rebel forces has continued, with the opposition reported to have advance west from their strongholds in the east of the country.

•International aid agencies are struggling to cope with the growing refugee crisis on Libya's borders as tens of thousands of foreign workers flee the fighting between pro- and anti-Gaddafi forces.

•Gaddafi has welcomed a proposal by Venezuelan president Hugo Chavez to mediate a peace settlement with the rebels. Opposition leaders in Benghazi said they were only open to talks about Gaddafi's resignation or exile.

•The director of the London School of Economics, Sir Howard Davies, has resigned over the university's links with Libya.

•A British man has died in the fighting after travelling to Libya to try and rescue his daughter.